Hi, I'm in need of some help as I can't seem to get this problem right.
Im trying to find the integral of 1/(9x^2+36x+81)dx
So, I started by completing the square and got int 1/[9((x+2)^2+5)] and consequently int 1/(9(x+2)^2+45).
I then turned 9(x+2)^2 into (3(x+2))^2 and factored out the 45 leaving me with (1/45) int 1/[1+(3(x+2))^2 I then used u-sub and made u 3(x+2) and eventually got (1/45)*(1/3) int du/1+u^2.
I know the derivative of arctan is dx/1+x^2 and ended up with
(1/135)arctan(3(x+2)). I know this isn't right as the online program I enter my answer in says its wrong.
If someone could help me out it would be much appreciated!